Control system for article stack wrapper



July 26, 1966 F. s. HYER CONTROL SYSTEM FOR ARTICLE STACK WRAPPER 5 Sheets-Sheet 1 Filed March 4, 1963 mmxov July 26, 1966 3,262,241

F. S. HYER CONTROL SYSTEM FOR ARTICLE STACK WRAPPER Filed March 4, 1963 5 Sheets-Sheet 2 July 26, 1966 F. s. HYER 3,262,241

CONTROL SYSTEM FOR ARTICLE STACK WRAPPER Filed March 4, 1963 5 Sheets-Sheet 4 8 TO SOL 9 T b To use TO SOL 8 TO SOL l3 5 7:: SOL 7 80L 6 6LS2 T0 SOL 6 l l O E 9LS2/ I 80 74 72 1 60 7 78 60 I F x 7-0 3L8! b T /50 76 soL 64 64 62 5% 62 To 7L5 T 70 L8! $0 SOL 9 50L 8 /.Mm

SYMM'W United States Patent 3,262,241 CONTROL SYSTEM FOR ARTICLE STACK WRAPPER Frank S. Hyer, Whitefish Bay, Wis., assignor to Cutler- Hanimer, Inc., Milwaukee, Wis., a corporation of Dela- Ware Filed Mar. 4', 1963, Ser. No. 262,428 7 Claims. (Cl. 53--55) This invention relates to article stack wrapper devices and more particularly to the electric and pneumatic control and interlocking of the operating steps of a newspaper stack wrapper.

A newspaper stack Wrapper is a complex machine which utilizes wrapping paper and an adhesive to form a wrap about four sides of a stack of newspapers. It is designed to accept and process the output of a newspaper stacking machine.

The process of stack wrapping consists of a series of distinct operations to be performed on the stack. These operations are accomplished by a number of mechanical devices, the operations of which must be coordinated to provide the necessary mechanical functions at the proper time and in the proper sequence. There must first be an apparatus to transport the stack of articles from the stacking machine to a position above the entry point of a Wrapping machine of a commercially available type where the stack is forcibly lowered by another device to intercept and be partially enveloped within a sheet of wrapping paper previously positioned below the stack by a wrap feed mechanism. The stack, when lowered into the wrapping machine, is positioned between two vertical walls which are horizontally movable to assist in conveying the stack through the wrapping machine. The wrapping paper covers the bottom of the stack and extends upwardly between the stack and the walls. As the stack subsequently travels through the wrapper, the stack is compressed and the upper ends of the paper are folded over the stack and are fastened together by gluing. Prior to such compression the top of the stack is horizontally offset slightly to compensate for deformation of the stack during compression. After fastening of the wrapping paper, the completed bundle is discharged.

It is an object of this invention to provide an electric and pneumatic control for a stack wrapper and more particularly to provide a sequential position stack wrapper control that safeguards against a catastrophic failure of the machine in the event that a malfunction of any portion of the sequence prohibits processing of the stack in succeeding portions of the machine.

It is another object of this invention to provide a control which will insure full cycling of the wrap feed mechanism and proper coordination thereof with the operation of the entire machine.

Further objects of the invention will be apparent upon reference in the following description and claims.

While the device hereinafter described is adapted to fulfill the objects stated, it is to be understood that it is not intended that the invention be confined to the particular preferred embodiment disclosed since it is suscepti ble of various modifications without departing from the scope of the claims.

Referring to the drawings:

FIGURE 1 is an isometric view of a stack wrapper;

FIGS. 2a and 2b when taken together show an electrical diagram of a control system incorporating the invention herein described;

FIGS. 3, 4, 5, 6 and 7 are partially diagrammatic and partially schematic views of various electrically and pneumatically operated elements of the machine;

3,262,241 Patented July 26, 1966 FIGS. 8 and 9 are partially diagrammatic and partially schematic illustrations showing top view of details of the control system; and

FIG. 10 is a partially diagrammatic and partially schematic illustration of an electrically and pneumatically controlled clutch and brake system utilized in the machine.

FIGURE 1 illustrates the overall arrangement of the elements of a newspaper stack wrapper and their relationship to a newspaper stacker unit 2. The stack wrapper itself consists of several units, a transfer unit 4, a loading unit 6, a wrap feed unit 8 and a bundle wrapping unit 10. The stacker 2 is of a type described in detail in Howdle et al. U.S. Patent No. 2,819,661 and now Reissue Patent No. 25,018. The transfer unit 4 and the loading unit 6 are preferably of a type more completely described in the F. S. Hyer copending application No. 262,414, now U.S. Patent No. 3,186,564, filed March 4, 1963. The bundle wrapper unit 10 includes a kicker 12 (FIG. 7) and a stack compressor which are described in detail in the F. S. Hyer et al. U.S. application No. 268,816, filed March 28, 1963.

The transfer unit 4 (FIGS. 1 and 3) is a reciprocating device used to transfer stacks of newspapers from the transfer units charging position at the discharge port 14 of stacker 2 to its discharge position in the interior of loading unit 6. A carriage 16 having stack supporting blades 18 travels between its charging and discharging positions by sliding on guide bars 20. A .pneumatic cylinder 22 provides the reciprocatory motive force to carriage 16 through a piston rod 24.

In FIG. 3, a top view of transfer unit 4, carrier 16 is shown in its charging position. Two cams 26 and 28 are attached to carriage 16 for the purpose of actuating limit switches 6LS and 12LS. Cam 26 is positioned to strike pivoted limit switch actuator 30 which is arranged to actuate limit switch 6LS only on the leftward stroke of carriage 4 from its discharging to its charging position. Cam 28 is arranged to trip limit switch 12LS as carriage 16 approaches its charging position and hold limit switch 12LS in tripped condition while carriage 16 remains in this charging position. A limit switch 8LS is positioned between blades 18 to be tripped by a stack of newspapers moving from left to right into the transfer unit from the stacker unit 2 (FIG. 1).

The movement of transfer unit 4 is controlled by the routing of compressed air to cylinder 22 through a selector valve 34, a spring biased shut off valve 36, a throttle valve 38 and a check valve 40. Compressed air is sup plied to the system through an air conduit 42. Selector valve 34 is alternately actuated by pusher solenoids SOL7 and SO L6. Valve 36 is spring biased to its closed position and may be opened by energization of pusher solenoid $01.10. When solenoid SOL-6 is energized, compressed air is directed by valve 34 to the right side of cylinder 22 to force piston rod 24 to the left. The air in the left end of cylinder 24 is exhausted through throttle valve 38, and if it is open, valve 36. If valve 36 is closed, the resistance to air flow of throttle valve 38 limits the flow from the left-hand side of cylinders 22 and thereby provides for cushioning of the movement of carriage 16 to its charging position. Check valve 40 closes when air is exhausted from the left end of cylinder 22. When selector valve 34 is moved to the right compressed air is directed from conduit 42 through check valve 40, throttle valve 38 and if it is open, valve 36, to the left side of cylinder 22 to drive piston rod 24 to the right. Air from the right side of cylinder 22 is free to exhaust to the atmosphere through selector valve 34.

The wrap feed unit (FIG. 1) includes a roll of paper 44 supported by stand 46 and paper cutting rolls 4 8 which cut paper strips 50 into lengths suitable for bundle wrapping as strip passes into the machine and under drop unit 6. A timing sprocket 52 (FIG. 9) in the wrap feed mechanism rotates once for each paper wrap fed to the stack wrapper. Cam 54 attached to sprocket 52 holds limit switch ILS open during the dwell period when the wrap feed mechanism is stopped between wrap feed cycles. Two electric motors are used to drive the feed mechanism. Motor M6 (-FIG. 2a) is mounted on paper stand 46 and feeds paper from roll 44 as required by the remainder of the wrap mechanism. A second motor M1 provides the motive power to insert paper strip 50 into the wrapping machine and to drive paper cutting rolls 48. The insertion of strip 50 and the action of cutting rolls 48 are controlled by brake 56 and clutch 58 which respectively stop the mechanism and couple motor M1 to the wrap feed mechanism.

After a stack has been transferred to loading unit 6 and properly positioned therein by carriage 16, a pair of drop gates 60 (FIGS. 1 and 4) close under the support blades 18 and behind the stack, thereby permitting the withdrawal of the carriage 16 and blades 18. The underturned lower edges 62 (FIG. 4) of gates 60 close under and support the stack. A pair of tabs 64 extend vertically from the ends of edges 62 to retain the stack when carriage 16 and support blades 18 are withdrawn.

Gates 60 are pivoted at their upper edges on shafts 66 and 68 and are interlinked and driven through a linkage comprising a lever 70 connected to shaft 66, a lever 72 connected to shaft 6 8, a link rod 74 connecting the upper end of lever 72 to the middle of lever 70, and a piston rod 76 driven by pneumatic cylinder 78. A cam 80 attached to shaft 66 actuates limit switch 9L5. The reciprocatory motion of piston rod 76 is controlled by a compressed air selector valve 82 which can be alternately actuated by two pusher type solenoids SOL8 and 501.9.

A ramming mechanism (FIG. 5) is mounted on top of the loading unit to forcefully lower the stack onto paper strip 50 when gates 60 are opened. A flat plate-like ram 84 is driven downwardly and raised by pneumatic cylinder 86 through piston rod 88. Also attached to ram 84 is a guide rod 90 having a cam surface 92 at its upper end for actuation of a limit switch 15=LS when ram 84 is at the lower end of its stroke. A compressed air selector valve 94, which can be alternately actuated by pusher solenoids SOL12 and SOL13, controls the movement of ram 84 by directing compressed air to either the top or bottom of cylinder 86.

When the stack is driven downwardly by ram 84 after having been released by gates 60, the stack intercepts the severed length of paper 50 and continues downwardly until it rests on a bed plate 96 (FIG. 1) which extends the length of the bundle wrapping unit 10. The length of paper 50 then covers the bottom of the stack and extends upwardly between the sides of the stack and opposing sidewall conveyors having lower sections 98 and 100 and upper sections 102 and 104. At that time the ends of the paper strip extend horizontally over the upper edge of upper sidewall conveyors 102 and 104.

The sidewall conveyors 98, 100, 102 and 104 are driven by electric motor M2 and are controlled by clutch 106 and brake 108 (FIG. 10). Both brake 108 and clutch 106 are pneumatically actuated, brake 108 being released and clutch 106 being engaged by an application of compressed air through air valve 110. A quick release valve 109 placed in the air line to clutch 106 serves to prevent simultaneous engagement of both the clutch 106 and brake 108. Valve 110 is spring biased to the position shown in FIG. 10 and can be actuated by pusher type solenoid SOL1.

A cam 112 is mounted on the upper end of a sprocket shaft 114 which rotates with a sprocket 116 of the upper sidewall conveyor 102. The cam 112 therefore trips limit switch 4LS once for each rotation of sprocket 116.

On the upper edges of each segment of upper sidewall conveyors 102 and 104 there are constructed paper grippers 118 (FIG. 6) which retain the ends of paper strip 50 when inserted by paper tucker blades 120.

The paper tucker mechanism is shown in FIG. 6. Each blade 120, of which there is shown an end view, is suspended from a lever 122. The two blades are interlinked by levers 124 and rod 126 and are driven through lever 128 by tandem pneumatic cylinders 130 and 132. Cylinder 130 is pivotally connected to lever 128 and connected to cylinder 132 through a common piston rod 134. Cylinder 132 is pivotally supported at pivot 136. Both cylinders are supplied through flexible conduits 138. A cam on piston rod 134 trips a limit switch 3LS when piston rod 134 is moved to the right by cylinder 132. A spring biased selector valve 142 controls cylinder 160 and can be actuated by a pusher solenoid SOL3. Another valve 144 controls cylinder 132 and can be alternately actuated by pusher type solenoid S0114 and SOLS.

It can be seen tucker blades 120 can be moved to three positions. The mechanism is shown in FIG. 6 in the intermediate position with piston 146 in the retracted position and piston *148 in the extended position. When both pistons 146 and 148 are in their extended positions, tucker blades 120 are driven downwardly to their lowest or inserted position to push the ends of paper 50 into paper grippers 118. When both pistons 146 and 148 are in their retracted positions, the tucker blades will be raised to their highest or fully retracted position.

FIGURE 7 illustrates a kicker mechanism which is mounted near the stacker end of the bundle wrapper unit 10. Pusher solenoid SOL11 actuates valve 150 to cause pneumatic cylinder 152 to drive kicker plate 154 to the right. Plate 154 is positioned to offset the top of the stack before the stack is conveyed away from under the loading unit 6. The purpose of the kicker mechanism is more elaborately explained in aforementioned US. application No. 268,816, filed March 28, 1963. As the stack is conveyed toward the stack wrapper exit 156 at the right end of the machine (FIG. 1), the stack wrap formation is completed and the paper 50 is glued by a hot melt type gluer unit 158.

To adjust the machine to accept various stack heights, bed plate may be raised or lowered on screw jacks 160 driven by a reversible motor M4 ('FIG. 2a).

The operation of the control system for the various elements of the stack wrapper will now be explained.

Referring to FIGS. 2a and 2b, electrical power is supplied through main conductors L1, L2 and L3. The wrap feed drive motor M1 is energized through the normally open contacts 5M1 of contactor 5M which is in turn energized through contacts 1MCR1 of control relay IMCR. The conveyor drive motor M2 is energized through disconnect switch DS and the power contacts 1M1 of contactor 1M. The roll stand paper feed motor M3 is energized through contacts 3M1 of contactor 3M. Motor M4 is energized to raise bed plate 96 when contacts 2U1 of contactor 2U are closed. To lower the bed plate 96, contacts 2D1 of contactor 2D are closed. The direction of movement is selected by switch 68 and the extent of movement is limited by limit switches 17LS and 18LS.

A power transformer PT with its primary connected across lines D1 and L2 supplies current to the remainder of the electrical system.

The gluer unit 158 has a glue heater 162 and a timer 164 which are energized through on-oif switch 15. An electric motor M6 closes contact ITS at intervals determined by timer 164 to energize contactor 4M to close contacts 4M1 and 4M2 which in turn energize gluer feed motor M5.

The control circuit for the wrap feed mechanism includes a pair of bi-stable latched relays 4CLR and 6CLR and an on-off switch 8S. A reset button 95 when depressed energizes coil 6CLRC to close contacts 6CLR2 and open contacts 6CLR1. This permits coil 4CLRC of the latched relay 4CLR to be energized by turning switch 88 to the on position. The energization of coil 4CLRC closes contacts 4OLR1 to permit operation of the tucker mechanism and closes contacts 4CLR2 to permit operation of the wrap drive mechanism.

The starting circuit includes a selector switch 25 with a test position and a run position. In the test position, a jog circuit 166 bypasses the normal starting and stopping circuit. The normal position of switch 25 is in the run position. Also included in the startmg circuit is an air pressure switch PS which will open to stop the machine if the air pressure supply of the various pneumatic devices falls below proper operating pressure.

The machine is started by momentarily depressing the start switch 48 to close contacts 481 and 482. The closure of contacts 482 completes a circuit through the normally closed jam switch 55 and the normally closed contacts 382 of a stop switch 38 to energize a control relay 7CR to close contacts 7CR1 in the start circuit and contacts 7CR 2 which maintain relay 7CR energized. Other contacts 7CR3, 7CR4 and 7CR5 also close to permit operation of other elements of the machine. The closure of contacts 7CR1 completes the starting circuit through switch 28, contacts 381, contacts 481 and pressure switch PS to energize control relay lMCR, contactor 3M and contactor 1M which closes circuit maintaining contacts 1M2.

At this point the machine is energized, the kicker plate 154 is retracted, the ram 84 is up, and the transfer carriage 16 is in its charging position ready to accept a stack of newspapers from the stacker 2. As a stack enters the transfer unit, its leading edge trips and closes limit switch 8LS to energize solenoid SOL7 and the transfer carriage 16 moves to its discharging position in loading unit 6. At the limit of its travel, transfer carriage '16 closes limit switch 7LS which in turn energizes solenoid SOL9.

When solenoid SOL9 is energized, drop gates 60 close to retain the stack and cam 80 trips limit switch 9LS, opening contacts 9LS1 to prevent accidental energization of solenoid SOL7 and closing contacts 9LS2 to energize solenoid SOL6. The energization of SOL6 returns the transfer carriage 16 to its charging position at the stacker 2. As carriage 16 approaches its charging position, cam 28 on carriage 16 opens limit switch 12LS to deenergize solenoid SOL10 and allow the spring biased valve 36 to close. The exhaust air from cylinder 22 is then routed through the throttle valve 38 to cushion the last few inches of travel of the transfer carriage 16. Limit switch 12LS is held open until the carriage 16 again moves from its charging position.

The operation of the ram 84 is initiated just after complete withdrawal of blade 18 from under the stack by the cam 26 on carriage 16 which momentarily trips limit switch 6LS opening contacts 6LS2. to prevent accidental energization of solenoid SOL12 and closing contacts 6LS1 to simultaneously energize solenoids SOL8 and SOL13. The energization of solenoid SOL8 causes the gates 60 to open and drop the stack. The de-energization of solenoid SOL12 and energization of solenoid SOL13 causes the ram to be driven downwardly on the stack.

As ram 84 reaches the bottom of its stroke, limit switch LS is tripped to cause the upward return of-ram 84 and to initiate the tucking operation and the wrap feed cycle. If, for some reason, an oversize stack were to be delivered to the loading unit 6, ram 84 will be stopped by the stack short of the position necessary to actuate limit switch 15LS and the raising of the ram and operation subsequent thereto would 'be' prevented. The stopping of the cycle at this point would forestall jamming of the oversize stack in the succeeding mechanical devices.

The closure of contacts 15LS1 picks up relay 5CR to close contacts 5CR1 which completes the circuit to solenoid SOL12 through contacts 6LS2 which have by this time closed after having been momentarily opened. The energization of solenoid SOL12 causes the raising of ram 84. Contacts 5CR2 maintain relay 5CR energized after contacts 15LS1 reopen as the ram is raised. The closing of contacts 5CR3 and the subsequent reclosing of contact 15LS2 as the ram 84 is raised energize solenoid SOL3 which lowers tucker blades 120. This order of operation insures that the pressure of ram 84 is relieved from the stack before the operation of tucker blades 120. At the same time the circuit to solenoid SOL3 is closed, a time delay relay 1TR of the on-delay type is energized. The energization of solenoid SOL3 and relay 1TR may also be accomplished manually by depressing the wrapper cycle button 65.

When relay 1TR times out, its contacts 1TR1 in the line of solenoid SOL4 close, retracting the right-hand cylinder 132 of the tucker mechanism, and contacts 1TR2 open to prevent energization of relay 1CR and solenoid SOLS. The movement of cylinder 132 trips limit switch 3L5, opening contacts 3LS2 to allow relays SCR and 1TR to drop out. When contacts 5CR3 open, solenoid SOL3 is deenergized and the left-hand cylinder 130 of the tucker mechanism retracts, causing the tucker blades to be raised to their highest or fully retracted position.

The tripping of limit switch 3LS also closes contacts 3LS1 to energize solenoids SOL1 and SOL11 and relay 20R. Energization of solenoid SOLl engages clutch 106 and releases brake 108 to start the sidewall conveyors 98, 100, 102 and 104 in motion. Solenoid SOL11 extends the kicker plate 154. As relay 2CR picks up, contacts 2CR1 close to effect energization of relay 3CR. Contacts 3CR2 open to prevent energization of solenoid SOLS. Contacts 3CR3 and 3CR4 open to prevent energization of coils 4CLRT and 4CLRC as long as relay 3CR remains energized. In addition, the wrap feed mechanism is put in motion when contacts 3CR6 open to deenergize solenoid BR and release brake 56 and contacts 3CR5 close to enenergize solenoid CL and engage clutch 58.

At this point the sidewall conveyors 98, 100, 102 and 104- are in motion transporting a stack to a new position and the wrap feed mechanism is inserting another sheet of paper 50 below the loading unit 6. It should be noted that the sidewall conveyor operation consumes substantially less time than the wrap feed cycle. The wrap feed mechanism is maintained energized until the end of its cycle by control means including limit switch lLS and cam 54 on the wrap feed mechanism. As cam 54 (FIG. 9) moves from the position shown, limit switch 1LS closes to maintain relay 3CR energized until cam 54 again opens limit switch 11.8 at the completion of the wrap feed cycle.

As the sidewall conveyors 98, 100, 102 and 104 are moving, the cam 112 momentarily trips limit switch 4LS which closes the circuit to the coil of relay ICR. Contacts 1CR1 close to bypass limit switch 4L8 to maintain relay 1CR energized. Iinterlock contacts 1CR3 open to insure that solenoid SOL4 is deenergized in preparation for the energization of the opposing solenoid SOLS. Contacts 1CR2 open to deenergize solenoids SOLI and SOL11 to stop the sidewall conveyors 98, 100, 102 and 104 and to retract the kicker plate 154. The opening of contacts 1CR2 also deenergizes relay 2CR to open contacts 2CR1 which in turn allows deenergization of relay 3CR when limit switch 1LS opens at the end of the wrap feed cycle. When relay 3CR drops out, contacts 3CR2 close the circuit to solenoid SOLS to move the tucker blades downwardly to their intermediate position. The dropping out of relay 3CR also closes contacts 3CR6 to apply brake 56 and open contacts 3CR5 to disengage clutch 58 thereby stopping the wrap feed mechanism. At the same time, contacts 3CR3 and 3CR4 close to make possible the energization of latched relay 4CLR.

The operating cycle of the stack wrapper control is completed at this point with the dropping out of relay 3CR. The stack now progresses in increments with each succeeding cycle to the exit 156.

The manually operated switch 88 is used to turn the wrap feed mechanism on and off. When switch 85 is in the on position and contacts 3CR4 and 6CLR2 are closed, coil 4CLRC will be energized to close contacts 4CLR1 in the tucker circuit and contacts 4CLR2 in the wrap feed circuit. When switch 88 is moved to the off position and contacts 3CR3 are closed, coil 4CLRT will be energized to open contacts 4CLR1 and 4CLR2. Contacts 4CLR1, when open, isolate solenoids SOL3 to prevent tucking action when the wrap feed mechanism is off.

The tucker mechanism and the wrap feed mechanism can be similarly rendered operative or inoperative by reset switch 98 or jam switches 2LS or 16LS. The jam limit switches 2L8 and 16LS are located in the wrap feed mechanism and will be closed by malfunctioning thereof. When either is closed, coil 6CLRT of bistable latch relay GCLR will be energized to open contacts 6CLR2 and close contacts 6CLR1 which causes latched relay 4CLR to render the tucker and wrap feed inoperative. As previously explained closing the reset switch 9S reverses this process.

It can be seen that latched relay 4CLR provides a jam prevention feature since the tucker and wrap feed mechanism may not be deenergized or energized by means of switch 85 while the wrap feed mechanism is in motion or in the middle of a cycle. Similarly, reset switch 98 and jam switches 2LS and 16LS will not cause operation of relay 4CLR until the end of the wrap feed cycle. These functions are delayed until the dwell period at the end of the wrap feed cycle because latched relay 4CLR cannot be energized until contacts 3CR3 and 3CR4 are closed and these contacts will not close until limit switch 1LS i tripped by cam 54 at the end of the wrap feed cycle.

Furthermore, the wrap feed mechanism may not be energized while the sidewall conveyors 98, 100, 102 and 104 are in motion because, as explained previously, relay SCR will be energized by contacts 2CR which close during the operation of the conveyors. It is important that, if the wrap feed is to be operated, its operation must be initiated with the energization of relay 3CR at the same time the sidewall conveyors are energized. Otherwise, there is a danger that limit switch 1LS, which sustains the operation of the wrap feed mechanism beyond the time required for movement of the sidewall conveyors, would not close before the end of conveyor movement and the wrap feed mechanism would stop in the middle of its cycle.

It can be further seen that relay GCLR, since it is a latched bistable device, provides a memory function in that the response to actuation of reset switch 98 or jam switches 2LS or 161.8, though delayed until the end of the wrap feed cycle, occurs even if the actuated switch reopens or power is momentarily lost before the end of the wrap feed cycle.

I claim:

1. In an article stack wrapping machine, transfer means operable to transfer an article stack from a first position to a second position, gate means operable to retain said stack at said second position after discharge from said transfer means and subsequently to release said stack, vertically reciprocatory means operable to forcibly lower said stack onto a length of wrapping paper following the release of said stack from said gate means, conveyor means including a pair of opposing side wall conveyors for transporting together said stack and said wrapping paper following the lowering of said stack and the attaching of said length of wrapping paper to said conveyor means, attaching means operable to attach the ends of said length of wrapping paper to said side wall conveyors following said lowering of said stack, offsetting means operable to offset the top of said stack following said lowering of said stack, wrap feeding means operable to supply another length of wrapping paper following said lowering of said stack, a plurality of power responsive means individual to each of the aforementioned means which, when energized, effect the operations of said aforementioned means, and control means including a plurality of electrical limit switches to coordinate and direct the energization of said power responsive means to effect the operations of said aforementioned means in the sequence described.

2. In an article stack Wrapping machine, transfer means operable to transfer an article stack from a first position to a second position, gate means operable to retain said stack in said second position after discharge from said transfer means and subsequently to release said stack, vertically reciprocatory means operable to forcibly lower said stack on to a length of wrapping paper following the release of said stack from said gate means, conveyor means including a pair of opposing side wall conveyors for transporting together said stack and said wrapping paper, wrap feeding means operable to supply lengths of wrapping paper, a plurality of power responsive means individual to each of the aforementioned means which, when energized, effect the operations of said aforementioned means, and control means for coordinating the operations of said aforementioned means, the means for operating said transfer means being responsive to the entry of a stack into said transfer means while in said first position to move said transfer means to said second position, the means for operating said gate means being responsive to movement of said transfer means to said second position to close said gate means and retain said stack, said means for operating said transfer means being responsive to the closing of said gate means to return said transfer means to said first position, said means for operating said gate means being responsive to the return movement of said transfer means to open said gate means, the means for operating said vertically reciprocatory means being responsive to the return movement of said transfer means to first lower and then raise said vertically reciprocatory means, the means for operating said attaching means being responsive to the raising of said vertically reciprocatory means to cause operation of said attaching means, the means for operating said conveyor means responsive to the operation of said attaching means to move said conveyor a predetermined distance and then stop said conveyor means, and the means for operating said wrap feeding means being responsive to completion of operation of said attaching means to operate said wrap feeding means to supply a length of wrapping paper within which a succeeding stack is wrapped.

3. The invention defined in claim 2, together with offsetting means operable to offset the top of the stack, means for operating said offsetting means, and control means for directing the operation of said offsetting means, said means for operating said offsetting means being responsive to said operation of said attaching means to operate said offsetting means.

4. The invention as defined in claim 2, in which said attaching means comprises tucker means for tucking said ends of said length of wrapping paper into paper grippers on the upper edges of said opposing side wall conveyors, said tucker means having a cycle of operation from an initial intermediate position to an inserted position to a fully retracted position and back to said intermediate position, said means for operating said attaching means being responsive to raising of said vertically reciprocatory means to move :said attaching means from said intermediate position to said inserted position, said means for operating said attaching means further including timer means responsive to the raising of said vertically reciprocatory means to initiate, after a predetermined interval, the movement of said tucker means from said inserted position to said fully retracted position, said means for operating said attaching means being further responsive to completion of operation of said wrap feeding means to move said tucker means from said fully retracted position to said intermediate position.

5. The invention as defined in claim 2, in which said raising of said vertically reciprocatory means in initiated by control means actuated in response to said vertically reciprocatory means reaching a preset position during its downward movement, whereby the raising of said vertically reciprocatory means and operations subsequent and in response thereto are prevented if said vertically reciprocatory means fails to reach said preset position on its downward stroke.

6. In an article stack wrapper, wrap feeding means, stack conveyor means, said wrap feeding means having a cycle of operation which consumes a greater period of time than the cycle of operation of said stack conveyor means, first control means operable to permit energization of said wrap feeding means, second control means for causing energization of said stack conveyor means and, when permitted by said first control means, for causing energization of said wrap feeding means, third control means actuated by movement of said wrap feeding means to maintain said wrap feeding means energized after said second control means deenergizes said conveyor means, and fourth control means actuated by movement of said stack conveyor means which prevents, during movement of said stack conveyor means, energization of said wrap feeding means consequent to operation of said first control means.

7. In an article stack wrapping machine; wrap feeding means having a fixed time cycle operation; and control means for energizing and deenergizing said wrap feeding means including first means operable at any time during operation or non-operation of said wrap feeding means to enable and prevent energization of the latter; said first means including bistable relay means which, when energized to the first of its stable positions, prevents initiation of said cycle of operation and which, when energized to the second of its stable positions, enables initiation of said cycle of operation; said first means further comprising second bistable relay means which is selectively energizable to either of two stable positions; said second bistable relay means, when in one stable position, permitting the first mentioned relay means to be energized to its first position and, when in the other position, permitting said first mentioned relay means to be energized to its second position; said control means further including second means responsive to said wrap feeding means being at any other than its starting point in its cycle of operation to prevent energization of said firs-t means to either position.

References Cited by the Examiner UNITED STATES PATENTS 2,675,657 4/1954 Taggart et al 53-58 2,991,603 7/1961 Zuercher 53-55 3,026,659 3/1962 Harrison 53-74 TRAVIS S. MCGEHEE, Primary Examiner. 

6. IN AN ARTICLE STACK WRAPPER, WRAP FEEDING MEANS, STACK CONVEYOR MEANS, SAID WRAP FEEDING MEANS HAVING A CYCLE OF OPERATION WHICH CONSUMES A GREATER PERIOD OF TIME THAN THE CYCLE OF OPERATION OF SAID STACK CONVEYOR MEANS, FIRST CONTROL MEANS OPERABLE TO PERMIT ENERGIZATION OF SAID WRAP FEEDING MEANS, SECOND CONTROL MEANS FOR CAUSING ENERGIZATION OF SAID STACK CONVEYOR MEANS AND, WHEN PERMITTED BY SAID FIRST CONTROL MEANS, FOR CAUSING ENERGIZATION OF SAID WRAP FEEDING MEANS, THIRD CONTROL MEANS ACTUATED BY MOVEMENT OF SAID WRAP FEEDING MEANS TO MAINTAIN SAID WRAP FEEDING MEANS ENERGIZED AFTER SAID SECOND CONTROL MEANS DEENERGIZED SAID CONVEYOR MEANS, AND FOURTH CONTROL MEANS ACTUATED BY MOVEMENT OF SAID STACK CONVEYOR MEANS WHICH PREVENTS, DURING MOVEMENT OF SAID STACK CONVEYOR MEANS, ENERGIZATION OF SAID WRAP FEEDING MEANS CONSEQUENT TO OPERATION OF SAID FIRST CONTROL MEANS. 